Flow press, especially flow sammying machine, for the production and processing of leather

ABSTRACT

In flow presses for the production and processing of leather, especially in sammying (drying) machines, the need exists for a preliminary effective stretching and widening of the leather to prevent the forming of creases. In a flow press with a pair of pressing rolls (W1, W2), there is arranged for this purpose in the zone of the entrance wedge (EZ) of the rolls, a stretching device (ARV) acting transverse to the flow direction (P1) of the leather, which is adjustable between an open position (OST) permitting introduction of the leather, and a working position (AST) with stretching tools (RW1, RW2) acting on the leather. This permits a perfect introduction of the leather, with visual control and with possibilities of correction. The slight distance attainable between the end section (EA) of the stretching tool and the roll pressing zone (PRZ), especially with non-rotating plate-form stretching tools, favors the suppression of creases in the pressing process.

The invention concerns a flow press, especially a flow sammying machinefor the production and processing of leather, with at least one pair ofrolls under mutual pressure, the flow line of pieces of leather to beprocessed preferably being provided with at least one suction and/orconveyor belt. Such flow presses and especially sammying machines, aregenerally known, and are used for the pressing processes necessary indifferent stages of leather production and processing, especially thosefor removal of fluid from the leather. These work steps and therespective machines are of great importance, in their effectiveness andtheir capacity, to the quality of leather and, respectively, to theefficiency of the whole production process.

A sammying is generally necessary at least twice, in the leatherproduction process, while special requirements are set, especially forthe first sammying, as to the quality and water content of the leather.In any case, however, folds (creases) in the leather during the pressingprocess are to be prevented so far as possible, and also creases presentbefore the pressing are to be removed, so far as possible. In known flowsammying machines, this stretching, which may have to be carried outrepeatedly, has been carried out in a separate work step, and withcorresponding separate devices, before the sammying. Also known in suchsammying machines is the use of blade cylinders which press the leatherto be sammied against the entrance-side conveyor or suction belt. Theseblade cylinders cause, essentially, just a more even lying of theleather against the entrance-side belt, but do not constitute a truestretching device. In any case, no substantial stretching and wideningeffect transverse to the flow direction, and thus no substantialreduction of creasing, is obtained in this way. In particular, theadhesive effect between suction or conveyor belts of the usual kind, onthe one hand, and the leather pressed against them, on the other hand,opposes a relative movement between leather and belt transverse to theflow direction and thus an effective stretching and widening process.

The problem of the invention, therefore, is to provide a flow sammyingmachine which makes possible, without separate work steps, in the verysame leather passage, a highly effective stretching and wideningprocess, preceding the sammying. The solution of this problem, accordingto the invention, is distinguished, in a flow sammying machine of thekind mentioned, by at least one stretching device, arranged in the zoneof the entrance wedge of the pair of rolls, acting at least partlytransverse to the flow direction, which is designed to be adjustablebetween an open position allowing the introduction of the leather, and aworking position with stretching tools acting on the leather.

Through such an arrangement of a stretching device, acting transverse tothe flow direction of the leather, in the zone directly before the zoneof the roll pressure, an intensive widening of the leather is obtainedwhich, because of the slight distance of this stretching and wideningzone before the subsequent flow pressing zone, is retained during theactual sammying and pressing process. The more or less strongcontraction of the leather before entering the roll pressing zone,inevitable when the stretching device is located at a greater distancebefore the roll pressing zone is prevented thereby, and an outstandingfreedom from creases is attained in the pressing process. At the sametime, the adjustability of the stretching device between workingposition and open position makes possible an introduction of theleather, already loosely widened and free of coarse folds, into the workzone of the stretching device and the entrance zone of the rolls.

According to one preferred form of execution of the invention, thestretching device has, on at least one surface side of the leather, astretching tool, at rest or moved opposite the flow movement, engaging,in the working position, in the entrance wedge of the pair of rolls.This engagement arrangement of the stretching tool in the entrance wedgeof the rolls, makes possible an especially slight distance between theoutlet of the stretching device and the entrance into the roll pressingzone. Even with leather with a stronger tendency to contraction andcreasing, a largely fold-free pressing and sammying process can beobtained. It is especially advantageous, in this connection, accordingto one development of the invention, to have the open position of thestretching device be set back, opposite the flow direction, in relationto the working position. This makes possible, even with greater rolldiameter, especially with a greater upper roll diameter, a relativelywide open position, such as that desirable for an ideal laying-inprocess, while, on the other hand, a deeper engagement of the stretchingtool in the entrance wedge of the rolls is retained in the workingposition.

In principle, it is true, rotating cylindrical stretching tools may beconsidered for the stretching device which, on their working side,rotate opposite the flow direction of the leather. However, theinevitable diameter and height extent of such rotating stretching toolsopposes the desired deep engagement in the entrance wedge of the rollsand thus makes impossible having only a slight distance betweenstretching tool and roll pressing zone. An important further developmentof the invention provides, therefore, that the stretching device have atleast one plate-form stretching tool, of which the rear end section,seen in the flow direction, in the working position, is arranged withinthe entrance wedge of the rolls. Such a stretching tool permits a designwith very slight thickness and height extent and in particular with endsection tapering in cross section, which can thus engage, in the workingposition, in the entrance wedge, just before the roll pressing zone.

The stretching device may be provided with cooperating stretching toolson both surface sides of the leather, especially with indentation-typecooperating complementary stretching elements. A further development ofthe flow press according to the invention, especially good as toproduction cost and particularly advantageous in handling, isdistinguished, however, by the fact that the stretching device has, onone surface side of the leather, an opposite support which can slide onthe leather, and which is preferably soft-deformable and yielding topressure, for at least one stretching tool arranged on the oppositesurface side of the leather. Such an opposite support is preferablyarranged on the under side of the leather, moving in a horizontal plane.The sliding surface quality of the opposite support, in relation to theleather, which is pressed by the stretching tool lying opposite, isimportant to the stretching and widening, because in this way, thenecessary relative movement, especially taking place transverse to theflow direction, between leather and opposite support, is not impaired.For many cases of use or qualities of leather, a rigid opposite supportwith surface which can slide, is sufficient, while the stretchingelements of the tool lying opposite, alone, through the frictionconnection with the leather surface or the compressibility of theleather, exert a sufficient stroking effect on the leather. Thisstroking effect may also, however, if desired, be supported andreinforced by the above-mentioned soft-deformable and pressure-yieldingproperty of the opposite support.

Another important further development of the invention provides that astretching tool opposite support of the kind mentioned is connected witha feed table for the leather to be processed or is designed, itself, asa feed table. This feed table is supported movable between a preparationand arranging position, placed forward, opposite the flow direction andan entrance position, placed behind, in the flow direction, engaging inan entrance wedge of the rolls. Such a design greatly facilitates andsimplifies the feeding and laying-in process, by the operator or by anautomatic feeding device, because the laying-in can be done in arelatively accessible position, favorable to the preparatory stretchingof the leather, and under visual control.

The combining of feed table and stretching opposite support or lowertool means, in this connection, an advantageous simplification ofconstruction and a considerable saving of space for the machine partsarranged in the entrance zone. In principle, however, such a feed-sidetable arrangement can also be used, independently of the presence of astretching tool, and thus in connection with other flow presses forleather production and processing. The subject of the invention extends,therefore, to this independent use of the feed table arrangement. Inthis connection, there may also be provided additionally, withparticular advantage, a feed conveyor belt for the leather pieces to beprocessed in the zone of the preparation and arranging position of thefeed table, which facilitates tending and makes possible an earlyarranging of the next piece of leather, in each case, before the returnof the feed table to its original position, that is, an increased workspeed.

Other features and advantages of the invention will be explained fromthe examples of execution represented schematically in the drawings,wherein:

FIG. 1 shows a flow sammying machine with integrated stretching device,in a schematic vertical section transverse to the arrangement of therolls, with stretching device in the open position.

FIG. 2 is a representation according to FIG. 1, but with stretchingdevice in the working position.

FIG. 3 shows a flow sammying machine with integrated stretching device,with a modified design of a stretching tool.

FIG. 4 is a perspective view of the working side of a plate-formstretching tool of FIG. 1.

FIG. 5 shows a stretching opposite support with pressure-yieldingcushioning, in cross section, in the working position with leather laidout and stretching tool of FIG. 1 in action.

FIG. 6 is a partial cross section of a stretching device as shown inFIG. 1 with two stretching tools, acting opposite and complementing eachother.

FIGS. 4, 5, and 6 depict two different embodiments of the stretchingdevice, either of which is usable with the apparatus of FIG. 1.

The flow press shown in FIGS. 1 and 2 is a sammying machine with tworolls, W1 and W2, supported axis-parallel, and under vertical mutualpressure, which, within the flow line DB (indicated in dot-and-dashline) of the pieces of leather L to be processed, forms a pressing orsqueezing zone PRZ. On the side of each of the two rolls W1 and Ww thereare conducted through the pressing zone PRZ suction or conveyor belts B1and B2. These are the usual felt strips, revolving endlessly andconducted over the corresponding turning and drive rolls. The flowdirection of the leather, in which the rolls W1 and W2 are driven by therespective belts B1 and B2 of an assembly of the usual kind, not shown,is indicated by the arrow P1.

The rolls W1, W2, with the respective suction or conveyor belts, form anentrance wedge EZ, into which, in each case, the front edge of the pieceof leather to be processed is introduced, to be caught by the belts B1,B2, running together and advanced into or through the pressing zone PRZ.Before the entrance EZ is connected a stretching device ARV, whichconsists mainly of a stretching tool RW1, arranged above the flow pathDB, and an opposite support WL, arranged below the flow path, for thestretching tool. The stretching device ARV also may include a secondstretching tool RW2, and also a pressing device APV. The stretching toolRW1 extends, in one piece or in sections lying side by side, over theworking width of the roll arrangement and is designed adjustable, byguides and drive means, ordinary and not shown in detail, according tothe double arrow P2, between an open position OST according to FIG. 1and a working position AST according to FIG. 2. In the open position,the entrance zone of the stretching device ARV and the entrance wedge ofthe roll arrangement are freed for laying in the front section of apiece of leather or for its entrance into the pressing zone PRZ. Theopen position is set back, in relation to the working position, oppositethe flow direction, according to the arrow P1, so that, on the one hand,a sufficient height position and a large entrance opening is availablefor the introduction of the leather, while, on the other hand, as canbeen seen from FIG. 2, the end section EA of the stretching tool RW1 canengage deeply into the entrance wedge EZ. This gives, as alreadymentioned in the introduction, the advantage of a slight distancebetween the end of the stretching device and the entrance into thepressing zone PRZ of the pair of rolls.

In the working position AST of the stretching tool RW1, the oppositesupport WL is pressed upward by a pressing device APV arranged below theentrance section of the belt B2; that is, against the leather in thestretching device and also against the stretching elements of thestretching tool lying above. This working pressure is provided by thepressing device through a pressure plate DR, which to compensate for anyinaccuracy of position of the stretching tool and variation of thicknessof the leather, is provided with a swinging support LG. The samearrangement may be used also in the instance where, instead of theunderlying opposite support WL, a second stretching tool RW2, withstretching elements complementary to the stretching tool RW11 lyingopposite, is provided. The structure of such stretching tools andopposite supports will be represented in detail farther on.

In the execution according to FIGS. 1 and 2, the opposite support WL orthe correspondingly arranged lower stretching tool RW2 is designed as afeed table ZT, movable parallel to the flow path DB according to arrowP3 between a preparation and arranging position VST (FIG. 1) and anentrance position EST (FIG. 2). Also, in the zone of the position VST ofthe feed table and above same, a smaller, endless revolving feed beltZB, with corresponding guiding and turning rolls, as well as a drive,not shown, is provided. When a piece of leather to be processed is laidon, this feed belt receives by its inclined upper section OT, falling inthe flow direction, the front section of the piece of leather to becoarsely widened first, and carries the latter in the flow directionuntil its front edge arrives in the zone before the entrance wedge EZ onthe entrance-side section of the belt B2 (FIG. 1). Then the feed tableis pushed forward from its position VST below the feed belt ZB, in theflow direction, synchronously with the belt B2, until its assumes itsentrance position EST (FIG. 2). Meanwhile, the feed table carriesforward with it the front section of the leather which lies on theopposite support WL or the lower stretching tool, as the case may be. Onreaching the entrance position, the front edge of the piece of leatherarrives in the entrance wedge EZ, and into the entrance zone of thepressing zone PRZ of the pair of rolls. Then the leather is caught bythe belts B1, B2, running together, and drawn into the pressing zone. Atthe same time, the upper stretching tool RW1 is lowered, and movedforward, according to the arrow P2, from its open position OST into theworking position AST. With this, the pressing of the leather iseffected, between the upper stretching tool RW1 and the opposite bearingWL beneath, or the correspondingly arranged stretching tool RW2. Theleather is now drawn steadily by the stretching device ARV, while thesuccessive sections of leather arrive, uniformly and already looselywidened, over the upper section OT and the discharge point LST of thefeed belt, into the entrance zone of the stretching device.

The stretching and sammying machine according to FIG. 3 differs from thedesign explained above (aside from the elimination of a feed belt forthe load of leather), by the use of a rotating stretching tool RW3instead of a plate-form stretching tool, at rest, against the upper sideof the leather. The stretching tool RW3, designed as a cylinder andprovided with strip-form stretching elements REL, rotates, at its underside, opposite to the flow direction P1, and exerts, through suitablyoblique positioning of the strip-form stretching elements, acorresponding stroking effect on the leather, directed transverse to theflow direction and parallel with the plane of the leather. Despite thesomewhat important advantage of the greater relative stroking speedbetween the stretching elements and the leather surface, such a designis subject to the limitation that on the under side of the leather nocomplementary stretching tool, acting on the leather by means ofcorrugations, but rather, only a smooth opposite support WL can be used.

The stretching tool RW3, as in the previous form of execution, ismovable, according to the arrow P2, between an open position OST' and aworking position AST'. In the open position, as in the previous design,the perfect entrance of the leather into the zone of action of thestretching device and the introduction of the front edge of the leatherinto the entrance wedge EZ and the pressing zone PRZ can be checked. Inthe opened entrance zone, moreover, an intervention is possible for thecorrection of any folds formed.

Contrary to the previous form of execution, with the use of a roll-formstretching tool RW3, according to FIG. 3, an equivalent shaping of thetransition zone between stretching device and roll pressing zone cannotbe attained. As appears from FIG. 3, even a relatively small rolldiameter of the stretching tool RW3 does not permit near approachcomparable to the design according to FIGS. 1 and 2, between the outletzone of the stretching device and the entrance zone of the pressingzone, because the roll diameter sets limits to the engaging of thestretching tool into the entrance wedge. The design with stationary, andin particular plate-form stretching tool, tapering to a point toward itsrear edge, is therefore generally more advantageous.

From FIG. 4 can be seen in detail the structure of the upper stretchingtool. Below the hollow profiled support body TR is formed a plate PL, ofwhich the surface extent substantially determines the stretching zone,and of which the rear end section EA engages, according to FIG. 2, intothe entrance wedge EZ of the pair of rolls. Against the under side ofthe plate PL are set strip-form or blade-form stretching elements REL,arranged divergent in the flow direction P1, which run obliquely outwardin opposite directions on both sides of the middle M of the conveyorpath. These stretching elements engage against the leather with frictionfitting and because of the pressure deformability of the leather, lyingon a solid, smooth opposite support surface, or in combination with acushion-like opposite support, also, form fitting, with correspondingcorrugations. With the sliding movement of the leather in relation tothe free lengthwise edges of the stretching elements, there is given thedesired stretching and widening effect, transverse to the flowdirection, and parallel to the plane of the leather.

The above-mentioned corrugation of the leather, with partly form-fittingattack of the stretching elements against the leather, is shown in FIG.5 in a schematic vertical section, of a cushion-type opposite support WL(in combination with a feed table ZT which can be pushed along). Thesame applies to stretching tools RW1 and RW2, arranged one above theother, with stretching elements REL arranged complementary, andcorrespondingly greater corrugation, as well as the stretching effect asrepresented in FIG. 6. In all cases, the result is that the elements ofthe stretching device coming in contact with the leather have a surfacequality which can slide sufficiently in relation to the leather, so thatthe relative movement necessary for the stretching process is not toogreatly hindered. In the examples of execution shown, this can beattained directly, because there is provided a constructive separationbetween the pressing and suction elements coming in contact with theleather, on the one hand, and the stretching elements, moved in relationto the leather, on the other hand.

What is claimed is:
 1. Apparatus for treating leather, comprising atleast one opposed pair of rolls between which the leather to be treatedis guided, means for moving the leather along a flow path from alocation spaced apart from said rolls to said rolls, stretching meansfor stretching the leather prior to its being guided between said rollsand comprising a first stretching tool disposed on one surface side ofthe leather and operable to stretchably engage the leather at a locationin the entrance wedge of said rolls at a distance from said rollswhereby the stretched leather does not contract prior to enteringbetween said rolls, and a feed table for feeding the leather to therolls, said feed table being movable between a first preparation andarranging position spaced apart from said rolls in a direction oppositethe flow path of the leather and a second entrance position in theentrance wedge of said rolls, said feed table having support means forsaid first stretching tool and disposed on the opposite surface side ofthe leather from said first stretching tool.
 2. Apparatus as defined inclaim 1 further comprising feed conveyor belt means adjacent said firstposition of said feed table.
 3. Apparatus as defined in claim 2 whereinsaid feed table when in its first position is disposed at leastpartially below the discharge point of said feed conveyor belt means. 4.Apparatus as defined in claim 1 wherein said first stretching toolcomprises a plate-form stretching tool having at least one pair ofstretching elements disposed divergent from the flow path of the leatherwhereby the leather is stretched at least partially in a directiontransverse to the flow path of the leather, said plate-form stretchingtool having a first end disposed within the entrance wedge of saidrolls.
 5. Apparatus as defined in claim 4 further comprising a secondstretching tool disposed on said support means on the opposite surfaceside of the leather from said first stretching tool, said secondstretching tool including at least one pair of stretching elementscomplementary to said stretching elements of said first stretching tool.6. Apparatus as defined in claim 1 wherein said stretching means furthercomprises support means for said first stretching tool disposed on theopposite surface side of the leather from said first stretching tool andslidably engaging the leather.
 7. Apparatus as defined in claim 6wherein said support means is resilient.
 8. Apparatus for treatingleather, comprising at least one opposed pair of rolls between which theleather to be treated is guided, means for moving the leather along aflow path from a location spaced apart from said rolls to said rolls,and stretching means for stretching the leather prior to its beingguided between said rolls, said stretching means being movable between afirst open position spaced apart from said rolls to allow an initialguiding of the leather into said rolls, and a second working position inthe entrance wedge of said pair of rolls, said first position of saidstretching means being spaced apart from said second position in adirection opposite to the flow path of the leather, said stretchingmeans comprising a rotating stretching tool adapted to rotatably engagethe leather in a direction opposite to the direction of the flow path ofthe leather, said rotating stretching tool having a plurality ofstretching elements disposed divergent from the flow path of the leatherwhereby the leather is stretched at least partially in a directiontransverse to the flow path of the leather, and a feed table for feedingthe leather to the rolls, said feed table being movable between a firstpreparation and arranging position spaced apart from said rolls in adirection opposite the flow path of the leather and a second entranceposition in the entrance wedge of said rolls, said feed table havingsupport means thereon for said first stretching tool disposed on theopposite surface side of the leather from said first stretching tool.